Diseases Home > Myasthenia Gravis and the Thymus Gland
Although the thymus gland is abnormal in adults with myasthenia, research scientists do not fully understand the relationship between myasthenia gravis and the thymus gland. However, some research scientists believe that the thymus gland may give incorrect instructions to developing immune cells, which results in autoimmunity and then leads to myasthenia gravis.
The thymus gland, which lies in the upper chest area beneath the breastbone, plays an important role in the development of the immune system. The thymus gland is somewhat large in infants, grows gradually until puberty, and then gets smaller and is replaced with fat as people age.
In adults with myasthenia gravis, the thymus gland is abnormal. It contains certain clusters of immune cells indicative of lymphoid hyperplasia, which is a condition that is usually found only in the spleen and lymph nodes during an active immune response. Some individuals with myasthenia gravis develop thymomas, which are tumors of the thymus gland. Although thymomas are usually benign, they can become malignant (cancerous).
The relationship between the thymus gland and myasthenia gravis is not yet fully understood. However, myasthenia research scientists have a few theories. For example, the thymus gland may give incorrect instructions to developing immune cells; this can result in autoimmunity and the production of the acetylcholine receptor antibodies, thus leading to myasthenia gravis.